Recently, oxide semiconductors have assumed a pivotal role in electronic displays and transparent electronic devices such as amorphous indium gallium zinc oxide (a-IGZO), characterized by high electron mobility and excellent stability. a- IGZO is very suitable for next-generation applications such as flexible displays because it is possible to manufacture highperformance transistors even at low temperatures. However, since the electrical properties tend to deteriorate in hightemperature environments, research aimed at improving thermal stability is needed. In this study, a low-temperature plasma annealing process was introduced to improve the high-temperature stability of the a-IGZO thin film. This process enhances electron mobility by reducing defects in the a-IGZO film and provides stable device performance even under high-temperature conditions. As a result of the experiments of 5 min, 10 min, 15 min, and 20 min, the a-IGZO TFT, which was subjected to plasma annealing at 160℃ for 5 min, showed the best electrical performance, especially in charge mobility and current-voltage characteristics. The technical potential for improving the performance of a-IGZO-based display device was emphasized, and the foundation for applying this power generation to flexible displays and next-generation electronic devices was laid. Future research will focus on determining the optimal annealing conditions by exploring various temperature ranges and plasma parameters to integrate these results into the actual device manufacturing process. These efforts are expected advance significantly to advancing next-generation high-performance display technology.
The display industry has recently been at the forefront of innovative advancements in modern electronic devices. Technological progress such as flexible display holds significant potential across various application fields, particularly in wearable devices and rollable displays. A low-temperature process is essential for fabricating such displays. One of the key technologies in displays is the thin film transistor (TFT), with amorphous indium gallium zinc oxide (a-IGZO) receiving particular attention. a-IGZO is widely applied in high-performance displays due to its high charge mobility and stability. While a thermal treatment above 350℃ is typically required to maximize the electrical performance of a-IGZO TFTs, such high temperatures pose challenges for utilizing polymer substrates like plastics. Here, we thesis investigates the simultaneous lowtemperature plasma annealing process to develop next-generation high-performance flexible display devices. To define the optimal temperature, devices were fabricated and analyzed at varying temperatures of 40℃, 80℃, 120℃, and 160℃. Experimental results indicated that devices fabricated at 160℃ and 80℃ exhibited superior performance, with those at 160℃ demonstrating better performance in terms of current ratio, threshold voltage, and subthreshold swing. These findings confirm that the simultaneous low-temperature plasma annealing process is effective for next-generation high-performance displays.
In recent years, the transparent amorphous oxide thin film transistor represented by indium-gallium-zinc-oxide (IGZO) has become the first choice of the next generation of integrated circuit control components. This article contributes an overview of IGZO thin-film transistors (TFTs), including their fundamental principles and recent advancements. The paper outlines various TFT structures and places emphasis on the fabrication process of the active layer. The result showed that the size of the active layer including the length-to-width ratio and the width could have a significant effect on the mobility. And the process of TFT could influence the crystal structure of IGZO thin film. Furthermore, the article presents an overview of recent applications of IGZO TFTs, such as their use in display drivers and TFT memories. At last, the future development of IGZO TFT is forecasted in this paper.
High reliability thin film transistors are important factors for next-generation displays. The reliability of transparent a-IGZO semiconductors is being actively studied for display applications. A plasma treatment can fill the oxygen vacancies in the channel layer and the channel layer/insulating layer interface so that the device can work stably under a bias voltage. This paper studies the effect of plasma treatment on the performance of a-IGZO TFT devices. The influence of different plasma gases on the electrical parameters of device and its working reliability are reviewed. The article mentions argon, fluorine, hydrogen and several ways of processing in the atmosphere. Among these methods, F (fluorine) plasma treatment can maximize equipment reliability. It is expected that the presented results will form a basis for further research to improve the reliability of a-IGZO TFT.
Oxide semiconductor devices have become increasingly important because of their high mobility and good uniformity. The channel length of oxide semiconductor thin film transistors (TFTs) also shrinks as the display resolution increases. It is well known that reducing the channel length of a TFT is detrimental to the current saturation because of drain-induced barrier lowering, as well as the movement of the pinch-off point. In an organic light-emitting diode (OLED), the lack of current saturation in the driving TFT creates a major problem in the control of OLED current. To obtain improved current saturation in short channels, we fabricated indium gallium zinc oxide (IGZO) TFTs with single gate and double gate structures, and evaluated the electrical characteristics of both devices. For the double gate structure, we connected the bottom gate electrode to the source electrode, so that the electric potential of the bottom gate was fixed to that of the source. We denote the double gate structure with the bottom gate fixed at the source potential as the BGFP (bottom gate with fixed potential) structure. For the BGFP TFT, the current saturation, as determined by the output characteristics, is better than that of the conventional single gate TFT. This is because the change in the source side potential barrier by the drain field has been suppressed.
Thin film transistors (TFTs) with large-area, high mobility, and high reliability are important factors for next-generation displays. In particular, thin transistors based on IGZO oxide semiconductors are being actively researched for this application. In this study, several methods for improving the reliability of a-IGZO TFTs by applying various materials on a passivation layer are investigated. In the literature, inorganic SiO2, TiO2, Al2O3, ZTSO, and organic CYTOP have been used for passivation. In the case of Al2O3, excellent stability is exhibited compared to the non-passivation TFT under the conditions of negative bias illumination stress (NBIS) for 3 wavelengths (R, G, B). When CYTOP passivation, SiO2 passivation, and non-passivation devices were compared under the same positive bias temperature stress (PBTS), the Vth shifts were 2.8 V, 3.3 V, and 4.5 V, respectively. The Vth shifts of TiO2 passivation and non-passivation devices under the same NBTS were -2.2 V and -3.8 V, respectively. It is expected that the presented results will form the basis for further research to improve the reliability of a-IGZO TFT.
Developing a thin-film transistor with characteristics such as a large area, high mobility, and high reliability are key elements required for the next generation on displays. In this paper, we have investigated the research trends related to improving the reliability of oxide-semiconductor-based thin-film transistors, which are the primary focus of study in the field of optical displays. It has been reported that thermal treatment in a high-pressure oxygen atmosphere reduces the threshold voltage shift from -7.1 V to -1.9 V under NBIS. Additionally, a device with a SiO2/Si3N4 dual-structure has a lower threshold voltage (-0.82 V) under NBIS than a single-gate-insulator-based device (-11.6 V). The dual channel structure with different oxygen partial pressures was also confirmed to have a stable threshold voltage under NBIS. These can be considered for further study to improve the NBIS problem.
In this study, we proposed an a-IGZO (amorphous In-Ga-Zn-O) TFT (thin-film transistor) with off-planed source/drain structure. Furthermore, two different electrode materials (ITO and Ti) were applied to the source and drain contacts for performance improvement of a-IGZO TFTs. When the ITO with a large work-function and the Ti with a small work-function are applied to drain electrode and source contact, respectively, the electrical performances of a-IGZO TFTs were improved; an increased driving current, a decreased leakage current, a high on-off current ratio, and a reduced subthreshold swing. As a result of gate bias stress test at various temperatures, the off-planed S/D a-IGZO TFTs showed a degradation mechanism due to electron trapping and both devices with ITO-drain or Ti-drain electrode revealed an equivalent instability.
In this study, we fabricate transparent and bendable a-IGZO (amorphous indium gallium zinc oxide) TFTs (thin-film transistors) with a-IZO (amorphous indium zinc oxide) transparent electrodes on plastic substrates and investigate their electrical characteristics under bending states. Our a-IGZO TFTs show a high transmittance of 82% at a wavelength of 550 nm. And these TFTs have an Ion/Ioff ratio of 1.8×108, a field effect mobility of 15.4 cm2/V·s, and a subthreshold swing of 186 mV/dec. The good electrical characteristics are retained even after bending with a curvature radius of 18 mm corresponding to a strain of 0.5% owing to mechanical durability of the transparent electrodes used in this study.
The conduction behavior and electron concentration change in a-IGZO thin-films according to the RTA (rapid thermal annealing) were studied. The electrical characteristics of TFTs (thin-film-transistors) annealed by different temperatures were measured. The sheet resistance, electron concentration, and oxygen vacancy of a-IGZO film were measured by the four-point-probe-measurement, hall-effect-measurement, and XPS analysis. The RTA process increased the driving current of IGZO TFTs but the VTH shifted to the negative direction at the same time. When the RTA temperature is higher than 250℃, the leakage current at off-state increased significantly. This is attributed to the increase of oxygen vacancy resulting in the increase of electron concentration. We demonstrate that the RTA is a promising process to adjust the VTH of TFT because the RTA process can easily modify the electron concentration and control the conductivity of IGZO film with short process time.
We have studied structural, optical and electrical properties of In-Ga-doped ZnO (IGZO) thin films. The IGZO thin films were deposited on the corning 1737 glass by RF magnetron sputtering method. The RF power in sputtering process was varied as 30, 50, 70, and 90 W respectively. All of the IGZO thin films transmittance in the visible range (400 nm ~ 800 nm) was above 83%. XRD analysis showed the IGZO thin films amorphous structure of the thin films without any peak. And also IGZO thin film have low resistivity (1.99×10-3 Ωcm), high carrier concentration (6.4×1020 cm-3), and mobility (10.3 cm2V-1s-1). By the studies we found that IGZO transparent thin film can be used as optoelectronic material and introduced application possibility for future electronic devices.
In this study, we fabricated the indium gallium zinc oxide (IGZO), zinc oxide (ZnO), aluminum zincoxide (AZO). oxide and silver are deposited by magnetron sputtering and thermal evaporator, respectively transparency and energy band gap were changed by the thickness of silver layer. To fabricate metal oxide metal(OMO) structure, IGZO sputtered on a corning 1,737 glass substrate was used as bottom oxide material and then silver was evaporated on the IGZO layer, finally IGZO was sputtered on the silver layer we get the final OMO structure. The radio-frequency power of the target was fixed at 30 W. The chamber pressure was set to 6.0×10-3Torr, and the gas ratio of Ar was fixed at 25 sccm. The silver thickness are varied from 3 to 15 nm. The OMO thin films was analyzed using XRD. XRD shows broad peak which clearly indicates amorphous phase. ZnO, AZO,OMO show the peak [002] direction at 34°. This indicate that ZnO, AZO OMO structure show the crystalline peak. Average transmittance of visible region was over 75%, while that of infrared region was under 20%. Energy band gap of OMO layer was increased with increasing thickness of Ag layer. As a result total transmittance was decreased.
We have investigated the effect of electrical properties of amorphous InGaZnO thin filmtransistors (a-IGZO TFTs) by post thermal annealing in O2 ambient.The post-annealed in O2 ambienta-IGZOTFT is found to be more stable to be used for oxide-based TFT devices, and has betterperformance, such as the on/off current ratios, sub-threshold voltage gate swing, and, as well asreasonable threshold voltage, than others do. The interface trap density is controlled to achieve theoptimum value of TFT transfer and output characteristics. The device performance is significantlyaffected by adjusting the annealing condition. This effect is closely related with the modulation annealingmethod by reducing the localized trapping carriers and defect centers at the interface or in the channellayer.
In order to prevent heat loss that occurs through the glass, low-emissivity (Low-E) coating methods with good insulating properties and high transmittance were used. lnGaZnO/Ag/InGaZnO (IGZO/Ag/IGZO) multilaver thin films have been deposited on XG glass substrate by HF magnetron sputtering. Depending on the different thickness of Ag in multilayer films, the structural and optical properties of Low-E multilayer films were analyzed. By XRI) analysis results, the multilayer thin films were observed to be amorphous structure regardless of Ag thickness. According to the AFM results, surface morphology of the multilayer films was observed and compared. Using UV-VIS spectroscopy, low emissivity propertty has been observed clearly with the transmittance of higher than 85% at visible range and lower than 30 at ll range.
In this study, The RF magnetron sputter and evaporator was on glass substrates 30 mm × 30 mm OMO multilayer thin film structure is applied to the low-e. Structural and optical properties, a thin film was produced, the variable was placed into a variable deposition time of the oxide layer. According to the XRD measurement results there is no peak that satisfies the Bragg`s law (2dsinθ= nλ) which confirmed that it is an amorphous structure. RMS value of the results of the AFM measurement, has a roughness of less than 2 nm. transmittance measurements results, visible light region an average 80%, IR region 40% showed.
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Influence on the Structure and Optical Properties of Ni-Nb Thin Films Based on Thickness 恒煕 崔 Modern Physics.2018; 08(04): 198. CrossRef
Comparison of the Properties of Almotriptan PVA Hydrogel Depending on the Ratio of PEG and Confirmation of Potential as Transdermal Formulation Se Mi Kang, Young Jin Jung, Jae Ho Lee Journal of Life Science.2014; 24(4): 437. CrossRef
IGZO thin films have been prepared by RF magnetron sputtering. The structural, electrical and optical properties of the IGZO thin films have been investigated as a function of deposition condition. XRD analysis of IGZO thin films showed a typical crystallographic orientation with c-axis perpendicular regardless of deposition conditions. The carrier mobility, carrier concentration and resistivity of the IGZO films sputtered at 200 W, 1mTorr and 300℃ were 28.5 cm2/V·sec, 2.6×1020 cm3, 8.8×10-4 Ω·cm respectively. The optical transmittance were higher than 80% at visible region regardless of the deposition conditions under the experiments above, and specifically higher than 90% at wave length over 500 nm. The absorption edge was shifted to shorter wavelength with increase of carrier concentration.
In this study, we fabricated an amorphous InGaZnO pseudo-MOS transistor (a-IGZO Ψ -MOSFET) with a stacked Si3N4/SiO2 (NO) gate dielectric and evaluated reliability of the devices with various thicknesses of a SiO2 buffer layer. The roles of a SiO2 buffer layer are improving the interface states and preventing degradation caused by the injection of photo-created holes because of a small valance band offset of amorphous IGZO and Si3N4. Meanwhile, excellent electrical properties were obtained for a device with 10-nm-thick SiO2 buffer layer of a NO stacked dielectric. The threshold voltage shift of a device, however, was drastically increased because of its thin SiO2 buffer layer which highlighted bias and light-induced hole trapping into the Si3N4 layer. As a results, the pseudo-MOS transistor with a 20-nm-thick SiO2 buffer layer exhibited improved electrical characteristics and device reliability; field effective mobility(μFE) of 12.3 cm2/V·s, subthreshold slope (SS) of 148 mV/dec, trap density (Nt) of 4.52× 1011 cm-2, negative bias illumination stress (NBIS) ΔVth of 1.23 V, and negative bias temperature illumination stress (NBTIS) ΔVth of 2.06 V.
Recently, amorphous oxide semiconductors (AOSs) based thin-film transistors (TFTs) have received considerable attention for application in the next generation displays industry. The research trends of AOSs based TFTs investigation have focused on the high device performance. The electrical properties of the TFTs are influenced by trap density. In particular, the threshold voltage (Vth) and subthreshold swing (SS) essentially depend on the semiconductor/gate-insulator interface trap. In this article, we investigated the effects of Ar plasma-treated SiO2 insulator on the interfacial property and the device performances of amorphous indium gallium zinc oxide (a-IGZO) TFTs. We report on the improvement in interfacial characteristics between a-IGZO channel layer and gate insulator depending on Ar power in plasma process, since the change of treatment power could result in different plasma damage on the interface.
In this paper, we have compared amorphous InGaZnO (a-IGZO) thin-film transistor (TFT) with the nano-crystalline embedded-IGZO (Nc-embedded-IGZO) TFT fabricated by solid-phase crystallization (SPC) technique. The field effect mobility (μFE) of Nc-embedded-IGZO TFT was 2.37 cm2/Vs and the subthreshold slope (S-factor) was 0.83 V/decade, which showed lower performance than those of a-IGZO TFT (μFE of a-IGZO was 9.67 cm2/Vs and S-factor was 0.19 V/decade). This results originated from generation of oxygen vacancies in oxide semiconductor and interface between gate insulator and semiconductor due to high temperature annealing process. However, the threshold voltage shift (△V(TH)) of Nc-embedded-IGZO TFT was 0.5 V, which showed 1 V less shift than that of a-IGZO TFT under constant current stress during 10(5) s. This was because there were additionally less increase of interface trap charges in Nc-embedded-IGZO TFT than a-IGZO TFT.
In this study, we investigated the optical, electrical, and structural properties of the IGZO(In2O3:Ga2O3:ZnO=1:9:90 wt.%) thin films prepared by RF-magnetron sputtering system under various substrate temperatures. All of the IGZO thin films shows an average transmittance of over the 80% in visible range. Most of all, deposited IGZO thin film at 100 ˚C substrate temperature have ZnO (002) of main growth peak and 17.02 nm of increased grains. And also IGZO thin film have low resistivity(1.35×10(-3) Ω·cm), high carrier concentration(6.62X10(20) cm-3) and mobility(80.1 cm2/Vsec). IGZO thin film have 2.08 mV at surface potential of electric force microscopy(EFM). We suggest that pre-annealing at 100 ˚C can be applied for improving optical, electrical and structural properties.
Effect of Ag Underlayer Thickness on the Electrical and Optical Properties of IGZO/Ag Layered Films So-Young Kim, Sun-Kyung Kim, Seung-Hong Kim, Jae-Hyun Jeon, Tae-Kyung Gong, Dong-Hyuk Choi, Dong-Il Son, Daeil Kim Journal of the Korean Society for Heat Treatment.2014; 27(5): 230. CrossRef
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